The one-day sale on Wednesday for members of Amazon's $99 per year Prime subscription service is similar to an annual sale by China e-commerce merchant Alibaba.
Wal-Mart Stores Inc also launched an online sale on Wednesday, a sign that the nation's largest retailer was concerned that Amazon was gaining market share, Gilford Securities analyst Bernard Sosnick said.
Discounts on products ranging from storage sets to robotic vacuum cleaners sent orders per minute at the peak higher than on "Black Friday, the term for the day after Thanksgiving, which traditionally has been the top retail sales day in the United States, Amazon said. It did not give detailed sales numbers but said it sold 35,000 Lord of the Rings Blu-Ray sets in 15 minutes and that a Kate Spade handbag was sold out in a minute.
Some Amazon shoppers vented on Twitter that Prime Day deals were selling out too quickly and complained that deals were not attractive enough.
Other shoppers used the #PrimeDayFail hashtag on Twitter. One user tweeted: "Hey @Amazon, #PrimeDay is not Black Friday in July. It's April Fools' in July. #primedayfail".
Adobe Digital Index said that 50 percent of overall sentiment related to Prime Day on social media was about disappointment.
"Much of the disappointed chatter focussed on the lack of blockbuster deals," it said, adding that users cited sales of less desirable items like socks and towels.
An Amazon spokeswoman said the retailer was listening to its customers and planned to add more deals like TVs.
ChannelAdvisor calculated the 80 percent rise in U.S. sales as of 12 p.m. ET (1600 GMT) based on sales by partner retailers that sell on Amazon.com.
Sales rose 40 percent in Amazon Europe, ChannelAdvisor said.
Amazon declined to comment on the data.
Wal-Mart launched a three-month online sale of some 2,000 items on Wednesday. The company said customers "shouldn't have to pay a fee" to get low prices, a dig at Amazon, which it did not name. Deals should be around for more than a single day, a spokesman said.
Target Corp has been running its own summer "Black Friday" sale since 2010 and is offering it for 10 days through Saturday.
© Thomson Reuters 2015